Artificial fabric containing resins



i Patented Apr. 3, 1934 UNITED STATES 1,953,083 ARTIFICIAL'VFABRI'C CONTAINING RESINS Walter E. Lawson, Wilmington, Del., assignor to E. I. du Pont de Nemours &. Company, Wil I mington, Del., a corporation of Delaware No Drawing. Application June 12, 1930, Serial No. 460,800. Renewed January 19, 1933 8 Claims. (Cl. 92-40) This invention relates to new and useful improvements in artificial fabrics and more particularly to fabrics formed from cellulose materials composed of fibers that have been artificially crinkled by chemical treatment and have been impregnated with certain artificial resins.

In prior methods of'preparing artificial fabrics from cellulosic fibers by the impregnation of rosin or natural resins or nitrocellulose, it has 3 been found that good products could be obtained but that such fabrics did not possess a very high resistance against tear or abrasion. It is an ob,-

ject of the present invention to prepare an artiflcial fabric from a cellulose base by the use of resins 'in'such manner as to have a resulting fabric that will have strong resistance against tear and abrasion as well as other desirable quali-' ties.

This object is achieved. by the following preferred form of procedure, although it will be understood that the invention is not limited thereto, as other modes of procedure may be adopted within the spirit of the invention.

The basic material for the fabric .consists of a fibrous cellulosic material prepared in a special manner as more particularly set forth in the application of McCormick 8; Schwartz application Ser. No. 283,445, filed June 6, 1928, of which Patent 1,857,100 is a continuation in part. A brief description of this process is as follows:

Wood or other suitable fibrous cellulose pulp is prepared in any suitable manner and is then treated with caustic alkali, for example, sodium,

potassium, or lithium hydroxide, in aqueoussolu-- tion at a concentration of from 8% to at room temperature for a short period of time insufficient to cause gelatinization of the cellulose fibers. This time treatment, with specially designed highly eificient mixing apparatus, is generally a matter of only several seconds. When using the ordinary beater, the time required is somewhat longer. In order 'to minimize the effect of time action of the strong caustic on the pulp, and for the sake of economy, the pulp is dispersed with the caustic at high pulp consistencies (low ratio of liquor to pulp) such as are disclosed in the examples of the mentioned application and condition. These cellulose fibers are then suitably pulped andfelted. For some purposes it is desirable to hvdratethe pulp before felting into paper and to this end the crinkled pulp is beaten in a standard paper-beating apparatus for a period of several hours, ranging, for example, from 2 to 12 hours. In this operation it is not desired to cut the fibers but merely to brush them out and hydrate them. Thereafter the fibers are deposited in the form of a web, as in known methods of manufacturing paper, and the web is thereupon dried.

The dried web is then passed into a solution of vinyl acetate polymer in butyl acetate in the proportion of 17% vinyl acetate polymer. There maybe added as softeners tricresyl phosphate, castor oil, dibutyl phthalate, or similar materials,

in the proportion of one part of vinyl acetate polymer to one-half part softener. The operation may be performed in ordinary impregnating apparatus. The content of vinyl acetate polymer will range from about 10% to as high as 50%, but preferably in the neighborhood of 35% in the finished sheet. After the impregnation the article is dried. It may thereafter be compressed to give it a finished appearance and may be calendered' or otherwise treated according to the usual practices in this art.

The resulting sheet has exceedingly valuable characteristics of great utility in the various arts for which such an article is adapted. Among its characteristics may be mentioned its great flexibility, its property of showing no paper-break when bentor sharply "flexed, its strong. resistance to tear and resistance to abrasion, and its good aging 'qualities. In reference to resistance to tear, it should be stated that the herein-described sheet will offer strong resistance against tearing by. hand, and when subjected to thestandard Elmendorf tester it will show a value of between 1100 and 1600 at a paper weight of .68 lbs. per 40', yard. These figures are on the basis of standard thickness of fabricof about .025 inch and of the aforesaid paper Weight. Other paper weights will, of course, produce variations proport-ionate to the paperweight.

The new articles of manufacture herein described are useful for bookbinding, bases for linoleum, bases for wall covering, auto top materials, auto interior coverings, furniture coverings, materials entering into the construction of shoes, and many other similar and. analogous uses wherein fabrics find employment. It should also be pointed out that this fabric is not laminated but consists of a single deposited sheet impregnated with the resin. It has been found, however, that a laminated sheet may be made by gluing together sheets as herein described or by putting on a multiple deposit during the papermaking step, and impregnating the paper with the resin. Furthermore, instead of laminating, the sheet may be made thicker than herein described so as to constitute a single deposited article equaling in its thickness 9. multiple deposited or a laminated sheet, and thereby securing advantages in flexibility and structural strength not possessed by laminated sheets. The latter is a particular advantage of this invention.

Besides vinyl acetate there may also be used meta styrene, vinyl proprionate polymer, vinyl butyrate polymer, vinyl chloride polymer, polymers of other vinyl compounds, or similar acetylene derivatives. There may also be used resins prepared by replacing the chlorine in polymerized vinyl chloroacetate with other groups. The use of these artificialresins in conjunction with this particular type of paper produces a very unexpected result different in type and kind from the aforesaid use of similar resins in ordinary paper. Thus, while such use of rosin in the early art produced a rosin-impregnated paper there was not the structural strength produced by the absorption of artificial resins in a mass of crinkled cellulosic fibers which, in conjunction with the resin, produced an inherently strong structure and hence one capable of great resistance against tear and abrasion. In the present invention the cellulose fibers may adsorb a considerable amount of resin, such as 5 0%, without having the article assume a glossy appearance, thus indicating the thorough nature of the impregnation. Varying percentages of resin may be adsorbed, for example: A sheet of prepared paper weighing 27.3 grams may be impregnated by immersion in a 50% solution of polymerized vinyl chloride. After rolling and drying the product, a tough, pliable article is obtained weighing 34.6 grams. Also, a sheet of prepared paper may be passed through a 20% solution of meta styrene containing tricresyl phosphate in a 10:8 ratio. After rolling and drying, thesheet is found to contain 24% of resin and plasticizer. The product is pliable and has an Elmendorf strength of 1040 grams with the grain and 1344 grams against the grain. stated here that different results will be obtained on the Elmendorf tester, as illustrated hereby, when the tear is made with, and against, the

grain.)

' pregnated with 27% of its weight of a mixture containing 2 parts polymerized vinyl acetate and one part tricresyl phosphate was coated in a coat- (It should be The coating showed excellent adhesion to the impregnated paper, and the product was tough and had good durability.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments thereof except as defined in the appended claims.

I claim:

1. An article of manufacture comprising a web of artificially crinkled cellulosic material impregnated with a vinyl ester polymer, said article being flexible, exhibiting no paper break, and having a strong resistance to tear.

2. The invention in claim 1 wherein the cellulosic material exists in the condition of hydrated, frayed, beaten fibers.

3. An article of manufacture comprising a web of artificially crinkled cellulosic material impregnated with a vinyl ester polymer, said article being flexible, exhibiting no paper-break, and having a strong resistance to tear, said web being substantially identical with the web obtained by dispersing paper pulp with 8% to 35% sodium hydroxide solution at room temperature, promptly washing out the caustic and felting the pulp.

4. An article of manufacture comprising a web of artificially crinkled cellulosic material impregnated with an artificial resin and nitrocellulose composition, said article being flexible, exhibiting no paper-break, and having a strong resistance to tear.

5. An article of manufacture comprising a web of artificially crinkled cellulosic material impregnated with a vinyl ester polymer and a plasticizing agent, said article being flexible, exhibiting no paper-break, and having a strong resistance to tear.

6. The article in claim 3 coated directly with a nitrocellulose composition without the interposition of a primer.

7. The process of manufacturing an artificial fabric which comprises treating wood pulp at high pulp consistencies with caustic alkali having a concentration of between 8% and 35% for a time not longer than 30 minutes, depositing a web of the treated fibres, impregnating the web with a vinyl ester polymer, and drying the sheet.

8. The'process of manufacturing an artificial fabric which comprises treating cellulose fibres in pulp form with caustic alkali having a concentration of between 8% and 35% for a short period of time, washing the treated fibres and dispersing them in water, beating the fibres in water for from 2 to 12 hours to brush them out and hydrate them without cutting them, depositing a web thereof, impregnating the web with vinyl ester polymer, and drying the sheet.

WALTER E. LAWSON. 

